This invention relates to an absorbent article such as sanitary napkins, incontinence liners, incontinence pads, discharge sheets, or the like to reduce dampness and prevent a body fluid from leaking down provided with a front surface sheet soft to skin having a decreased area in contact with the skin and a manufacturing method therefor.
Conventionally, front surface sheets of absorbent articles provided in the market are provided with appropriate emboss patterns depending on various purposes such as eliminating skin troubles by means of decreasing an area in contact with skin, providing texture, increasing a spot absorbency, or the like. One of this kind includes the prior art described below, for example.
Firstly, as illustrated in FIG. 11, Japanese Unexamined Patent Application Publication No. 2002-165830 proposes a front surface sheet 50 for an absorbent article in which concave and convex shapes are formed in a skin abutment side when worn. When the absorbent article using the front surface sheet 50 is worn, the concave and convex shapes are transformed flexibly following a body shape and movement, and the concave portion of the concave and convex shapes captures high-viscosity excreta so as to separate said high-viscosity excreta and the body.
As illustrated in FIG. 12, Japanese Unexamined Patent Application Publication No. 2004-174234 proposes a front surface sheet 51 for an absorbent article used in a skin abutment side of the absorbent article. The proposed sheet comprises a top layer consisting of a sheet-like material which faces the skin side of a wearer and substantively does not expand and a bottom layer consisting of a sheet-like material which is arranged in an absorber side and substantively does not expand, and said top layer and said bottom layer are partially bonded so as to form numerous bonding portions. Said to layer protrudes to the skin side of a wearer in other area except said bonding portion, forming numerous convex portions hollow inside. The convex portion and the bonding portion are arranged alternately forming columns in one direction, and further a plurality of said columns are arranged such that with respect to any one of convex portions in one column, in the right and left columns adjacent to said column, the convex portion is not adjacent to the convex portion.
The front surface sheet of the absorbent article of Japanese Unexamined Patent Application Publication No. 2002-165830 presented a problem in that since the convex portions and concave portions (bonding portions) were continuing in one direction linearly in parallel and the convex portion was continuing in one direction, an air passage which significantly reduced the dampness was created, however, since the concave portions (bonding portions) were also continuing in one direction, a body fluid easily leaked down along the concave portions as flow channels.
In contrast, in the case of the front surface sheet of the absorbent article of Japanese Unexamined Patent Application Publication No. 2004-74234, it presented a problem in that since the convex portions and the concave portions were arranged in a zigzag pattern and had excellent absorbency to prevent a body fluid from leaking down, however, the air did not easily pass through, creating dampness.
The main object of this invention is to provide an absorbent article to reduce dampness and prevent a body fluid from leaking down, provided with a front surface sheet soft to skin having a decreased area in contact with the skin and the manufacturing method therefor.
As the invention of a first aspect of the invention, in order to solve the problem, an absorbent article with an absorber disposed between a permeable front surface sheet and a rear surface sheet of a non-woven fabric is provided, in which the front surface sheet is provided with convex portions in a ridge shape continuing in a longitudinal direction of the absorbent article at a specified interval in the width direction of the absorbent article and provided with dot like concave embossments at a right side adjacent position and a left side adjacent position alternately at an interval in the longitudinal direction of the absorbent article on the both sides of each convex portion, and the concave embossments are arranged in a zigzag pattern as a whole.
According to the aforementioned first aspect of the invention, the front surface sheet is provided with a ridged convex portion continuing in the longitudinal direction of the absorbent article at a specified interval in the width direction of the absorbent article. The concave embossments (bonding portion) securing the front surface sheet is provided with dot-like concave embossments at the right side adjacent position and the left side adjacent position alternately at an interval in the longitudinal direction of the absorbent article on the both sides of each convex portion. The concave embossments are arranged in a zigzag pattern as a whole.
Therefore, the convex portion continuing in the longitudinal direction creates an air passage to reduce dampness. Since the concave embossments securing the front surface sheet are arranged in a zigzag pattern in dots at the right side adjacent position and the left site adjacent position alternately at an interval in the longitudinal direction of the absorbent article on the both sides of each convex portion, the passage of the body fluid becomes a zigzag pattern defined by the concave embossments, thereby preventing the body fluid from leaking down.
Furthermore, even if the body fluid passes through the front surface sheet to flow into the convex portion, the passage in this convex portion alternately expands and shrinks the passage width such that the body fluid does not flow easily and yet is easily absorbed in the absorber side, thereby preventing the body fluid from leaking down.
In a second aspect of the invention, in the absorbent article of the first aspect of the invention, in the front surface sheet in a cross section passing the concave embossment in the width direction, an inclined surface to the concave embossment on the side adjacent to the convex portion is relatively steep,
an inclined surface to the concave embossment on the side distant to the convex portion is relatively gentle, and the cross sectional shape of the convex portion is asymmetrical.
Thus, the second aspect of the invention is related to the cross sectional shape of the convex portion, in which an inclined surface to the concave embossment on the side adjacent to the convex portion is relatively steep, an inclined surface to the concave embossment on the side distant to the convex portion is relatively gentle, and the cross sectional shape of the convex portion is asymmetrical with the top as the border.
Therefore, it is possible to reduce the skin contact area, and when a body pressure is received from the front surface side, the cross-sectional shape of the convex portion forms an asymmetrical form bordering the top, and the both walls of the convex portion has a smaller resistance force than the resisting asymmetrical shape to the pressure which is easier to collapse, hence the area becomes softer to the skin.
As a third aspect of the invention, in the absorbent article of the second aspect of the invention, the height of the convex portion is 1-3 mm and the height at the center point position of the inclined surface having a gentle gradient is 0.5-2 mm.
The third aspect of the invention defines the height dimension of the convex portion of the front surface sheet. Specifically, it is desirable that the height at the top of the convex portion be 1-3 mm and the height at the center point position (a half point of a distance between the top and the concave embossments) of the inclined surface having a gentle gradient be 0.5-2 mm.
As a fourth aspect of the invention, in the absorbent article of any of the first to third aspects of the invention, in which regarding the concave embossments, it is desireable that their dimension in the longitudinal direction of the absorbent article is 0.3-4 mm, their dimension in the width direction of the absorbent article is 0.3-3 mm, and their center-to-center interval in the longitudinal and the width directions of the absorbent article is 2-15 mm.
As a fifth aspect of the invention, the manufacturing method of the absorbent article described in any of the first to fourth aspects of the invention is provided, wherein:
the front surface sheet is inserted between a pair of first concave convex roll and second concave convex roll facing each other so as to form the convey portion and concave embossments;
regarding the first concave convex roll, a convex strip portion continuing in the line direction is formed at an interval in the line width direction, the convex strip portion is a wavy convex strip portion with a left convex curved portion protruding to the left side and a right convex curved portion protruding to the right side alternately repeated in a planar view, and the inner surface side of the left convex curved portion and the inner surface side of the right convex curved portion are an arc-shaped curved portion;the second concave convex roll has a dot-like convex portion at a position corresponding to the arc-shaped curved portion on the inner surface side of the left convex curved portion of the first concave convex roll, and a dot-like convex portion at a position corresponding to the arc-shaped curved portion on the inner surface side of the right convex curved portion, and these dot-like convex portions are arranged in a zigzag pattern;after the front surface sheet is inserted between the first concave convex roll and the second concave convex roll, it is removed from the first concave convex roll to rotate while it is maintained on the second concave convex roll side. Thereafter, it is introduced between the second concave convex roll and the flat roll provided facing each other, and a second sheet non-woven fabric is introduced between the second concave convex roll and the flat roll such that the front surface sheet and the second sheet non-woven fabric are bonded at a position corresponding to the dot-like convex portion of the second concave convex roll; andin the subsequent assembly process, an absorber is placed on the top sheet of the rear surface sheet and on the top thereof a front surface sheet in which the second sheet non-woven fabric is laminated on the entirety of the bottom surface side is placed.
The fifth aspect of the invention relates to the manufacturing method of this absorbent article, defining the manufacturing method of a particularly suitable front surface sheet.
Specifically, it is a common method in that the convex portion and the concave embossments are provided in the process of inserting between a pair of first concave convex roll and second concave convex roll facing each other, however, according to this manufacturing method the first concave convex roll, a convex strip portion continuing in the line direction is formed at an interval in the line direction, the convex strip portion is a wavy convex strip portion with a left convex curved portion protruding to the left side and a right convex curved portion protruding to the right side alternately repeated in a planar view, and the inner surface side of the left convex curved portion and the inner surface side of the right convex curved portion are an arc-shaped curved portion.
In contrast, the second concave convex roll has a dot-like convex portion at a position corresponding to the arc-shaped curved portion on the inner surface side of the left convex curved portion of the first concave convex roll, specifically a substantial center point position of the arc-shaped curved portion on the inner surface side and a dot like convex portion at a position corresponding to the arc-shaped curved portion on the inner surface side of the right convex curved portion, specifically at a substantial position of the arc-shaped curved portion on the inner surface side, and these dot-like convex portions are arranged in a zigzag pattern.
The convex strip portion of the first concave convex roll to form the convex portion of the front surface sheet is not to be formed linear but the wavy convex portion in which the left convex curved portion protruding to the left and the right convex curved portion protruding to the right in a planar view are alternately repeated. The inner surface side of the left convex curved portion and the inner surface side of the right convex curved portion are an arc-shaped curved portion, and the dot-like convex portion of the second concave convex roll to form the concave embossments in the front surface sheet is positioned at a substantial center point position of what is surrounded by the arc-shaped curved portion.
Therefore, since the dot-like convex portion of the second concave convex roll is at the substantial center point position of what is surrounded by the arc-shaped curved portion of the first concave convex roll, and the distance from this dot-like convex portion to the arc-shaped curved portion of the first concave convex roll is substantially equal, it is possible to prevent the front surface sheet from being cut off effectively in order to give the concave embossments.
The convex strip portion of the first concave convex roll is the wavy convex strip portion, however, the ridged convex portion formed on the front surface sheet in a product is formed substantially linear due to the restoration force of the non-woven fabric.
As detailed above according to this invention, it is possible to provide an absorbent article to reduce stuffiness and prevent a body fluid from leaking down, provided with a front surface sheet soft to skin having a decreased area in contact with the skin.
Furthermore, according to the manufacturing method of this invention, in order to emboss the front surface sheet, it is possible to give concave embossments at a position adjacent to the convex portion while preventing the sheet from being cut off.